Broken Crankshaft?? WTH :/

[Ricky Gee]

Update;
I was able to get the engine tore down and didn’t see any reason for the crank to just break. Looking at the crank it looks like a bad casting and it finely gave way. Ive got 2 other engines, one of them seems to be free and only has 34K on it. It has been sitting for awhile and its condition is unknown. It does spin free though, so hopefully i have a runner. It’s an earlier model, looks to be a 78 0r 79 which seems to be the better years. Looks like they did some changes in 1980 that slightly detuned it? Crossing my fingers that i have a good one. It will get a good look over before i install it.
i do have a question, I couldn’t get the alternator rotor off the crank and the broke crank wont come out of the case till it’s removed. What’s the secret? I have a puller but it wouldn’t budge.
Thanks for the inputs..

[bikerphil]

A 16mmX1.5 bolt threaded into the rotor and using an impact gun, the rotor will fall right off.

[Ricky Gee]

Bikerphil

i am a little slow this morning and I'm not following you here. I don't remember seeing a place to thread a bolt into the rotor other than the center bolt that holds the rotor in place. Can you help clear the cobwebs out of me?? LOL

[bikerphil]

Look at again, there are threads in the rotor and the bolt pushes against the crank popping the rotor off.

[DEEBS11]

[DEEBS11]

Many of these to choose from on the internet.

[Ricky Gee]

This make sense. I was thinking the bolt that held the rotor used those thread. Now to find the bolt required. thanks guys.

[DiverRay]

The bolt to remove it is 16mm X 1.5mm X 45mm. I'm buying a new one to use from Tacoma Screw, and they have a 50mm that has threads all the way up. 1.25" is all you should need for bolt length, 50mm is about 1.75". Yeah, not exact, but close enough for government work....

[Ricky Gee]

thanks all.. still looking locally for the correct bolt. i may have to order it if i cant find one.

[DiverRay]

Google search for metric bolts near you. Tacoma Screw is a large company, and has offices in most metro areas. Granger may also carry a bolt that will work.

[bikerphil]

A few pics of the rotor pulling process...

[Ricky Gee]

Update

finely got my engine back together, I have to admit it was quite the challenge. Heck of time with my fat fingers getting the piston pin retainers back in, then getting the cams timed. I get them in place and timed, place the cam tensioner in place only to rotate the engine to the C and hear the cam chain slip on the crank. Figured out i had a bad tensioner. I installed the one out of the blown engine and it worked. Now to do a leak down check the sure all of them are holding. Touched up the frame and hopefully get it back in the bike this weekend. excited to get this old war horse back on the road again. I forgot to mention, I discovered it had a big bore kit installed. 74.5 1196 cc

[Larrym]

My fingers are cossed fOaR you... ( •_•)

FWIW... adjusting a cam chain tensioner per the repair manual instructions AFTER it and the cam chain have been properly installed by the factory is easy as PIE and just as safe. (^_^)

BUT... next time you wanna install a cam chain and THEN install the CCT? (O_o)

Make gravity and the design of the engine wurky FoAr you instead of against you by rotating the engine (or the entire bike if necessary....) so that's the front of the engine is UP, not FWD. (O_O)

The slack of the chain (by design...) is intended to be gathered at the front of the engine wheres the CCT (when in place and properly adjusted...) applies just enough pressure to remove the slack AND keep the chain from falling down/off the lower sprocket teeth. ( ๑‾̀◡‾́)σ

BUT... when the engine is in the "nurmal" riding/running orientation gravity GOTS to pull the chain DOWN and OFF the bottom teeth iffin the CCT ain't THERE doin' it's jorb. (⇀‸↼‶)

Putting the front of the engine in the UP orientation lets gravity pull the slack in the NEW down direction which is the same direction the CCT would'a been FORCING the slack by design. So's even w/o the CCT gravity keeps tension on the cam chain and mOaR importantly...keeps it tensioned against the lower sprocket teeth whilst yur rotating the chain to line everything up. (◕‿◕)

Note- R/R'ing the CCT on an already working/running bike with the engine in the nurmal and upright orientation without the HEROICS needed to keep the chain frum falling like in yur situation? (O_o)

REALLY bad track record and well documented on this forum. (－‸ ლ)

[skids]

Update

I forgot to mention, I discovered it had a big bore kit installed. 74.5 1196 cc

What a NICE find!!!